Long Horizontal Well Completion via a New Flotation Technique

Abstract

The objective of the paper is to introduce a new technology which secures long horizontal casing deployment by a reliable casing flotation technology. It is common nowadays to drill a slim hole and extends to long horizontal extension to pay zones in condensate and shale oil and gas reservoir. To assure a successful casing deployment into the horizontal section, a flotation collar is often installed to float the casing in horizontal to mitigate the friction and Torque & Drag. However, slim casing may encounter difficulty in circulation and subsequent cementing even after the collar is broken. A new proprietary technique proposed in this paper solved above contingencies and secured 100% success in casing deployment, This technique secures smoothly circulation and cementing by flotating air in horizontal casing interval and purging air out of hole to overcome Spring Effect before circulation and cementing. Often, the flotation collar is made of proprietary material that can break or explodes under certain hydraulic pressure. After breaking, the whole collar becomes a portion of casing with exact the same ID of casing or a very small difference that does not have any negative effect to subsequent Plug & Perf, frac, tools running through and fluid movement. For long horizontal length of small open hole and casing sizes, casing deployment may be difficult if the Torque & Drag and friction through the low sides can not be mitigated. This paper proposes a new technique to fill air full of horizontal interval along inside the casing and ensure a sufficient of air purging to overcome Spring Effect before circulation and cementing. So far twelve (12) wells have been successfully completed including Asian longest horizontal gas well with 7,388.18m measured depth and 4,118.18m horizontal length. All jobs are 100% successful and there is no difficulty in mud circulation and cementing. Even for the longest 4,118.18m horizontal length casing deployment, the hook weight on surface when casing reached the total depth still remained 20 MT. Before this technique was applied, operators were unable to deploy 4 ½" casing through a 6" bit hole beyond 1500m horizontal length. Most often the hook weight at surface were zero when casing extended to almost 1500m in horizontal length. This new technique brings a great value to operators to complete longer horizontal well to yield more production with less investment.